Mucoadhesive curcumin nanospheres: biological activity, adhesion to stomach mucosa and release of curcumin into the circulation.

Although mucoadhesive drug carriers for the gastro-intestinal tract (GIT) have been reported, the mucoadhesive property and drug release characteristics have never been evaluated separately, whilst the adherence of the carriers to the surface of GIT has not been directly visualized. Here, a monopolymeric carrier made from ethylcellulose (EC) and a dipolymeric carrier made from a blend of methylcellulose (MC) and EC (ECMC) were easily fabricated through a self-assembling process and yielded the highest reported curcumin loading of ~48-49%. Both curcumin loaded ECMC (C-ECMC) and curcumin loaded EC (C-EC) particles showed an in vitro free radical scavenging activity and a dose-dependent in vitro cytotoxic effect towards MCF-7 human breast adenocarcinoma and HepG2 hepatoblastoma cells in tissue culture. The in vivo evaluation of their adherence to stomach mucosa and their ability to release curcumin into the circulation were carried out through quantification of curcumin levels in the stomach tissue and in blood of mice orally administered with the two spheres. Direct evidence of the adherence of the C-EC and C-ECMC particles along the mucosal epithelia of the stomach is also presented for the first time through SEM images. The mucoadhesive property of self-assembled C-EC nanoparticles is discussed.